Acclimation and endogenous abscisic acid in the moss Physcomitrella patens during acquisition of desiccation tolerance

Authors: RATHNAYAKE, KUMUDU - University Of South Dakota; Nelson, Sven; Seeve, Candace; Oliver, Melvin; KOSTER, KAREN - University Of South Dakota

Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/26/2018
Publication Date: 10/23/2019
Citation: Rathnayake, K.N., Nelson, S.K., Seeve, C.M., Oliver, M.J., Koster, K. 2018. Acclimation and endogenous abscisic acid in the moss Physcomitrella patens during acquisition of desiccation tolerance. Physiologia Plantarum. https://doi.org/10.1111/ppl.12892.
DOI: https://doi.org/10.1111/ppl.12892

Interpretive Summary: Physcomitrella patens, a moss that can be grown in lab cultures, has become a common model organism for studying how plants respond to dehydration and what plant hormones control the response. In this study, we looked at which environmental drying treatments could induce the ability of this plant to withstand desiccation, the severest of dehydration. We determined that if we acclimated the plant to a mild stress for 12 days it could then survive a subsequent severe dehydration to a desiccated state, while plants acclimated to mild stress for less time did not subsequently survive the severe stress. We also determined the involvement of the plant hormone, abscisic acid (ABA), in the response and concluded that the cells of the plant at two developmental stages require a significant exposure to ABA in order to generate the capability of surviving desiccation. These results help us to understand how an acclimation period of mild stress and plant hormones can play an important role in how plants survive in stressful environments. This is important information as we move forward to deliver crops and management strategies that can provide sustained yields under drought conditions.

Technical Abstract: The moss Physcomitrella patens use as a common model organism to study desiccation, but the effects of acclimation period and accumulation of endogenous abscisic acid (ABA) on desiccation tolerance (DT) and recovery are less studied. In this study, P. patens was acclimated at 89% relative humidity (RH) for up to 12 d prior to desiccation at 33% RH, and results demonstrate that acclimation can induce DT to water potentials below -150 MPa in both protonema and gametophore stages. During acclimation, significant endogenous ABA accumulation occurred after 1 d in gametophores and after 2 d in protonemata. ABA tissue distribution was examined using the ABA-inducible EARLY METHIONINE promoter fused to a cyan fluorescent protein (CFP) reporter gene, and the distribution of the CFP throughout the tissues was mostly uniform. DT was measured by day 6 of acclimation in gametophores, but not until 9 d of acclimation for protonemata. These results suggest that endogenous ABA that accumulates when moss cells experience moderate water loss during acclimation must have sufficient time to induce the changes that permit cells to survive more severe desiccation. These results provide insight for ongoing studies of how acclimation induces metabolic changes to enable DT in P. patens.